JP2000187304A - Photographic image forming member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a transmissive display material that ensures improved light transmission and more effectively diffuses light so that an illumination light element is not seen by an observer. SOLUTION: The photographic image forming member contains at least one photosensitive silver halide layer present in the top part of the member at least one photosensitive silver halide layer present in the bottom part of the member and a polymer sheet with at least one layer of a voided polyester polymer and at least one layer containing a non-voided polyester polymer. The image forming member has 38-42% transmittance and further contains a colorant. The thickness of the non-voided layer is at least two times that of the voided layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to photographic materials.
The present invention, in a preferred form, relates to a substrate material for use in transmissive photographic displays.

[0002]

BACKGROUND OF THE INVENTION Photographic display materials are known in the art for use in decorative displays of advertising and photographic images. Since these display materials are used in advertising, the image quality of the display material is important to represent the quality message of the advertised product or service. In addition, photographic display images need to have a strong impact because they are trying to draw the consumer's attention to the display material and the desired message being conveyed. Common uses of display materials include advertising of products and services in public places such as airports, buses and sports stadiums, movie posters and art photography. Desirable attributes of high quality, high impact photographic display materials are minimal blue density, durability, sharpness and flatness. Cost is also important because display materials tend to be expensive compared to other display material technologies, mainly lithographic images on paper. In the case of display materials, traditional color paper is undesirable because of the disadvantages of lack of durability for handling, photographic processing and display of large format images.

[0003] When producing color paper, the base paper is
It is known that a layer of a polymer, generally polyethylene, is applied. This layer serves to impart water resistance to the color paper and to provide a smooth surface on which the photosensitive layer is formed. Producing a suitably smooth surface is difficult, and proper laydown of the polyethylene layer is difficult.
n) requires great care and expense to guarantee cooling. Producing a suitably smooth surface also improves image quality. This is because the display material is more clearly specular in black because the improved reflective properties of the substrate are more specular than conventional materials. The whiter the white part, the blacker the black part, and the larger the area between them, the higher the contrast. It would be desirable to be able to produce more reliable and improved surfaces at lower cost.

Prior art photographic photographic papers have a melt-extruded polyethylene layer which also serves as a carrier layer for whitening agents such as optical brighteners and tinting agents. It would be desirable if the optical brightener, whitening agent, and tint could be concentrated near the optically more efficient surface rather than being dispersed within a single polyethylene melt-extruded layer.

[0005] Prior art photographic display materials are typically optimized for transmissive or reflective display materials. Therefore, photofinishing laboratories need to stock two types of display materials. Furthermore, when the illumination light source for the transmissive display material is turned off, the image quality as reflective is unacceptable.

[0006] Prior art transmissive photographic display materials incorporating a diffuser have a light sensitive silver halide emulsion coated directly on a gelatin-coated transparent polyester sheet. An integrated diffuser is necessary to diffuse the light of the light source used to backlight the transmissive display material. Without a diffuser, the light source would degrade image quality. Generally, a white pigment is coated on the bottommost layer of the imaging layer. Since gelatin is used as a binder in photographic emulsions, light sensitive silver halide emulsions tend to be yellow, so the minimum density areas of the developed image tend to appear yellow. The public who sees the image,
Yellowish white reduces the commercial value of transmissive display materials, as it relates image quality to whiter whiteness and furthermore, yellowish white is perceived as old. Desirably, the transmissive display material incorporating the diffuser has a more bluish white.

[0007] Prior art transmissive display materials use high coverage light-sensitive silver halide emulsions to increase the density of the image as compared to photographic reflective print materials. Increasing the coverage increases the density of the image in the transmissive space, but also increases the time required to develop the image as the coverage increases. In general, high density transmissive display materials require a development time of 4 times for photographic print materials.
This is 110 seconds compared to less than 5 seconds. Processing prior art high density transmissive display materials reduces the productivity of the lab. In addition, coating a high coverage emulsion requires additional drying of the emulsion during manufacture, reducing the productivity of the emulsion coater. Desirably, the transmissive display material has a high concentration and a development time of less than 50 seconds.

Prior art transmissive photographic display materials incorporating a diffuser have a light sensitive silver halide emulsion coated directly on a transparent polyester sheet primed with gelatin. Individual elements of the illuminating lamp to be utilized, in order to sufficiently diffuse light so as not to be visible to the viewer of the displayed image, the TiO _2, added to a layer of the bottommost part of the image forming layer.

[0009] However, coating the image forming layer with TiO ₂ causes production problems such as an increase in the coating amount, and an increase in the coating amount requires a larger drying capacity of the coating machine. In addition, TiO ₂ requires additional cleaning of the coater, which lowers the productivity of the coater. In addition, the use of large amounts of TiO ₂ for diffusing the backlighting system of a high intensity, TiO ₂ coated in the bottommost imaging layer reduces the quality of the transmitted image causing scattering of unacceptable light. It is desirable to remove TiO ₂ from the image layer and still provide the necessary transmission and image quality characteristics.

An example of an improvement and limitation of the coextruded thin layer technique is described in US Pat. No. 5,476,708, in which sharpness improvements in photographic systems are used under photosensitive emulsions. It has been proposed to achieve this by a tinted, pigment-free melt-extruded lamina made as described above. The thin layer underlying the emulsion is coextruded, microvoided, biaxially stretchable and required for a rigid and more efficient diffusion layer, and yellowing of the photosensitive silver halide imaging layer. It would be desirable if a blue tint could be provided to provide color correction.

[0011]

SUMMARY OF THE INVENTION Light transmission is improved,
At the same time, there is a need for transmissive display materials that more effectively diffuse light so that the light source elements are not visible to the viewer.

It is an object of the present invention to provide an improved transmissive display material. Another object of the present invention is to
It is to provide a display material that provides low cost and durable sharp images. Yet another object of the present invention is to more efficiently use the light used to illuminate the transmissive display material. It is also an object of the present invention to provide a display material that functions as both a transmissive display material and a reflective display material. It is yet another object of the present invention to provide a product that provides a silver halide image on both sides, but can still maintain a single exposure step and short processing.

[0013]

SUMMARY OF THE INVENTION These objects of the invention are addressed by at least one photosensitive silver halide layer at the top of a photographic imaging member and at least one photosensitive silver halide layer at the bottom of the member. And a polymer sheet having at least one layer of a voided polyester polymer and at least one layer comprising a non-voided polyester polymer, wherein the imaging member has a transmittance. Is achieved by a photographic imaging member which contains 38 to 42%, further contains a tinting agent, and wherein the thickness of the non-voided layer is at least twice the thickness of the voided layer.

[0014]

DETAILED DESCRIPTION OF THE INVENTION The present invention has many advantages over conventional transmissive display materials and methods of imaging transmissive display materials. The display materials of the present invention can diffuse light very efficiently while simultaneously transmitting light at a high rate. The layers of the coextruded polyester sheet of the present invention contain adjusted levels of voids, optical brighteners and colorants to provide optimal transmission properties. Its polyester sheet has without the use of expensive TiO ₂ or other white pigments, a voided layer to efficiently diffuse the light of a common illumination light source in transmissive display material. The co-extruded polyester substrate of the present invention has a transparent polyester layer that provides rigidity without compromising light transmission. The ratio of the thickness of the voided layer to the thickness of the transparent layer is at least 1: 2. If the thickness ratio is less than 1: 2, the voided layer is too thick,
Because the image cannot be illuminated, the support cannot provide sufficient illumination to obtain a good quality image.

[0015] The polyester sheet of the present invention preferably has a coextruded integral emulsion adhesive layer.
On top of the transparent layer and the voided layer, a corona-discharged co-extruded polyethylene layer can be used as the silver halide emulsion adhesion layer, eliminating the need for a primer coating commonly practiced on polyester sheets. . A corona discharge treated polyethylene layer is preferred. Because without the need for primer coating,
This is because gelatin-based silver halide emulsions adhere well to polyethylene. Further, the skin layer of the integral polyethylene can also contain a bluing agent and a fluorescent whitening agent, thereby offsetting the inherent yellowness of the gelatin-based silver halide emulsion. The voided stretched polyester sheet of the present invention is also low cost. This is because the functional layer is co-extruded and does not require further processing such as lamination, priming or extrusion coating.

In a preferred embodiment, the material has a silver halide image forming layer on both sides of a polymer sheet, and can form an image with a collimated beam exposure apparatus in one exposure. Because there are two relatively thin layers of silver halide imaging material, the developer solution rapidly penetrates through these thin layers of imaging material to provide rapid development of the elements of this invention. Can be. This co-extruded microvoided polymeric material sheet is made in a single step and therefore has low cost. Prior art products are typically two-step systems or introduce a bottom color layer during emulsion coating with a reduced drying load and coating process.

To produce a transmissive display material,
There is a need for display materials that sufficiently diffuse light so that the individual elements of the lamp used are not visible to the viewer. On the other hand, light needs to be transmitted efficiently in order to brightly illuminate a display image. The present invention can now use a large amount of illumination light as illumination for a display, while at the same time diffusing the light of the light source very efficiently, making the light source invisible to the viewer. Although the display materials of the present invention appear whiter to the viewer than prior art materials, the prior art materials require a large amount of light-scattering pigment to prevent individual light sources from being seen, and therefore are somewhat yellow. Tend to look. These high concentration pigments appear yellow to the viewer, making the image darker than desired. The production of transmissive display materials requires display materials that sufficiently diffuse light so that the individual elements of the lamp used are not visible to the viewer. On the other hand, light
In order to brightly illuminate a display image, it is necessary to transmit light efficiently. The present invention can now use a large amount of illumination light as illumination for a display, while at the same time diffusing the light of the light source very efficiently, making the light source invisible to the viewer. Although the display materials of the present invention appear whiter to the viewer than prior art materials, the prior art materials require a large amount of light-scattering pigment to prevent individual light sources from being seen, and therefore are somewhat yellow. Tend to look. These high concentration pigments appear yellow to the viewer, making the image darker than desired. These and other advantages will be apparent from the detailed description below.

The terms "top", "top", "emulsion side" and
“Omote” as used herein refers to a polyethylene layer
Or the direction of that side. The terms "bottom" and "bottom"
`` Side '' and `` back '' are the sides or sides opposite the polyethylene layer.
Means the direction of that side. The term "transparent"
As used herein, radiation without significant deflection or absorption
It refers to the ability to penetrate lines. In the case of the present invention, "transparent
"Nana" material is a material with a spectral transmittance of more than 90%
Fee. For photographic elements, the spectral transmittance is
This is the ratio of the transmitted intensity to the incident intensity.
Expressed as a fraction: T _RGB= 10^-D× 100 [where D
Is X-Ritemodel 310 (or equivalent)
Red, green and blue stays measured with a photographic transmission densitometer
The average value of the Tass A transmission density response]. The term "two
A "duplitized" element, as used herein,
Coating of photosensitive silver halide on the top and bottom of the imaging support
Means an element that has

The layers of the coextruded polyester sheet of the present invention contain controlled levels of voids, optical brighteners and colorants to provide optimal transmission properties. The biaxially oriented polyester sheet is a multi-layer substrate having a transparent polymer substrate and a microvoided lamina for efficient diffusion for backlighting applications, enhanced image processing and product handling of display assemblies. Extruded as

An important aspect of the present invention is that the photographic support can be coated on its top and bottom with a photosensitive silver halide emulsion. This dual coating is preferred when high density transmission images are required. The double silver halide coating described above in combination with the optical properties of a stretched polyester sheet provides an improved transmissive photographic display material that can be used for high quality transmissive images.
Prior art photographic display materials that increase dye concentration by increasing the emulsion coverage on one side,
The dual display material of the present invention has significant commercial value in that it requires 110 seconds compared to 45 seconds for the product of the present invention.

It has been found that the ratio of the top side to the bottom side coverage of the double emulsion is preferably in the range of 1: 0.6 to 1: 1.25. It has been found that when the ratio of coverage on the top side to the bottom side of the double emulsion is 1: 1.25, the imaging light is large and inversely attenuated, resulting in underexposure of the bottom emulsion coating. In contrast, the ratio of the top side to the bottom side coverage of the double emulsion was 1: 0.6.
Below, the imaging light was greatly and inversely attenuated and the top emulsion coating was overexposed. The preferred ratio of the top side to the bottom side coverage of the double emulsion is 1: 1.
It is. A 1: 1 ratio can achieve the necessary exposure and dye density required to obtain a high quality image.

In the case described above, the photographic imaging element has light-sensitive silver halide and a dye-forming coupler in both the top and bottom layers. To provide a photographic element in this application, one preferred structure comprises at least one photosensitive silver halide layer on top of a photographic imaging member, and at least one photosensitive silver halide layer on the bottom of the member. And a polymer sheet having at least one layer of a voided polyester polymer and at least one layer comprising a non-voided polyester polymer, wherein the imaging member has a transmittance. 38-42%
A photographic imaging member further comprising a tinting agent and wherein the thickness of the non-voided layer is at least twice as thick as the voided layer.

This is preferred because it provides an optimal integrated diffusion screen that is part of the base element structure. This diffusion characteristic is very desirable for backlight applications. When coating the back side with a gelatin-based emulsion,
Since gelatin does not adhere well to polyester, a backside primer or primer coat is required. Further, in contrast to the gelatin subbing layer, a polyethylene layer is desirable for enhancing the adhesion on the back side of the silver halide emulsion. If both sides of the substrate are coated with a light-sensitive silver halide emulsion, both sides need to be corona treated before applying the first light-sensitive layer to the substrate (otherwise the emulsion would be foggable). Please be aware that there is.

In the case of double emulsions, it may be desirable to further include a photographic element having an antihalation layer on the outermost portion of the back emulsion. The antihalation layer is generally a layer consisting of gelatin having "black" silver or exposed silver. The purpose of such a layer is to provide improved sharpness and to prevent re-exposure of the silver halide from light once passed through the emulsion.

If stretched, any polyester sheet suitable for the member can be used.
Stretching imparts additional strength to the multilayer structure and enhances handling characteristics when the display is assembled. Microvoided stretched sheets are preferred. This is because, without using TiO ₂ , the voids provide opacity. The microvoided layer is usually made by extruding the core layer and the lamina and then biaxially stretching, thereby forming a void around the voiding initiator contained in the lamina.

The layer thickness of the sheet can be between 76 μm and 256 μm, preferably between 80 and 150 μm. Microvoided sheets of thickness less than 80 μm are not thick enough to minimize the inherent handling and kinking problems when handling large sheets of this material. If the thickness exceeds 150 μm, there is little improvement in surface smoothness or mechanical properties, and there is no good reason to add expense for additional materials. For preferred photographic imaging members, the microvoided layer should be between 6 and 50 microns thick. If the thickness of the voided layer is less than 6 μm, the diffusion characteristics of the layer will be minimal, and if it is greater than 50 μm, it will be more opaque, hindering the quality of backlight applications with a silver halide emulsion on the backside.

The term "void", as used herein, means that the voids appear to contain gas but no added solids and liquids. The void-inducing particles remaining in the core of the finished packaging sheet must be 0.1-10 μm in diameter, preferably circular, to produce voids of the desired shape and size. In addition, the size of the void depends on the degree of stretching in the vertical and horizontal directions. Ideally, the void will take the form defined by two concave discs facing each other and in contact. In other words, the voids tend to have a lens-like or biconvex shape. As the voids are stretched, the two main dimensions are oriented in the longitudinal and transverse directions of the sheet. The Z direction is a secondary dimension, which is approximately the size of the cross-sectional diameter of the void-forming particles. Since voids generally tend to be closed cells, there is virtually no open path for gas or liquid to pass from one side of the voided core to the other.

In the case of the uppermost biaxially oriented layer on the emulsion side, the preferred classes of thermoplastic polymers for the biaxially oriented sheet and core matrix polymer of the preferred composite sheet include polyolefins. Suitable polyolefins include polypropylene, polyethylene, polymethylpentene, polystyrene, polybutylene and mixtures thereof. Polyolefin copolymers, including copolymers of polypropylene with ethylene such as hexene, butene and octene, are also useful. Polypropylene is particularly preferred because of its low cost and desirable strength properties. The polyethylene layer may have at least one of the polymer substrate sheets, and in particular may include a layer on top of the voided layer. Another means of increasing the adhesion of the silver halide photographic emulsion on the polyester polymer surface of the image forming material of the present invention is to apply a subbing layer. A typical subbing layer can include materials known in the art that facilitate adhesion to polyester, and can further adhere the subbing layer to gelatin.

Additives may be added to the top skin layer to change the color of the imaging element. For photography, a slightly bluish white substrate is preferred. Add a slight bluish color by mechanically mixing the color concentrate before extrusion.
This can then be accomplished by methods known in the art, including melt extruding a premixed blue colored material at the desired mixing ratio. 320 to simultaneously extrude the skin layer
Coloring pigments that can withstand extrusion temperatures above 320 ° C. are preferred because temperatures above 100 ° C. are required. The blue coloring material used in the present invention may be any coloring material that does not adversely affect the image forming element. Preferred blue coloring materials include
Phthalocyanine blue pigments, chromophtal blue pigments, Irgazin blue pigments, and Irgalite organic blue (Irga)
light organic blue) pigments.

It has been found that a very thin coating (0.2 μm-1.5 μm) can be made on the surface directly beneath the emulsion layer by coextrusion followed by stretching in the machine and transverse directions. It has been found that this layer is inherently very accurate in thickness and can be used to provide any color correction distributed throughout the sheet thickness between the emulsion and the paper substrate. The top layer is so efficient that the total amount of colorant required to correct is less than half the amount required if the colorant is dispersed throughout the thickness. Colorants often produce point defects due to poor clamping and dispersion. Point defects (reducing the market value of an image) are improved using the present invention. Because less colorant is used and the total weight of the polymer containing the colorant is typically only 2-10% of the total polymer between the base paper and the photosensitive layer, This is because high quality filtration is very suitable for cleaning the layer.

When the biaxially stretched sheet is viewed from the crowd,
Additives may be added to the polymer sheets of the present invention so that the imaging element emits light in the visible spectrum when exposed to ultraviolet light. When emitting light in the visible spectrum, the support can have the desired bag land color in the presence of ultraviolet energy. This is particularly useful when viewing images outdoors. Because sunlight contains ultraviolet energy, it can be used to optimize image quality for consumer and commercial applications.

The technology that emits visible light in the blue spectrum
Additives known in the art are preferred. Consumers generally
1b of zero^*B in units^*Achromatic color defined as
Slightly bluish to negative b compared to small concentrations^*Set as
It prefers to the minimum density area of the defined image. b^*Is CIE
A measure of the space's yellow / blue. Positive b^*Is Ye
Indicates low, negative b^*Indicates blue. Blue spec
Add additives that emit light at Torr to reduce the whiteness of the image
Tint the support without adding any colorant
Can be. Preferred luminescence is 1-5Δb^*Is a unit.
Δb^*Means that the sample is illuminated with UV light and significant UV light
B measured for a light source without energy^*Difference and constant
Justify. Δb^*Is the fluorescent material on the top biaxially stretched sheet of the present invention.
Good for confirming the net effect of adding photo brightener
It is a measure. 1b^*Light emission smaller than the unit
Consumers cannot be aware. Therefore, the polymer layer
The addition of an optical brightener does not cause a difference in perception,
Not cost efficient. 5b ^*Light emission larger than the unit
The color balance of the lint is lost, and as a result most
Consumers see the white area as too blue.

The preferred additives of the present invention are optical brighteners. Optical brighteners absorb ultraviolet light and emit it as visible blue light. It is an organic compound that emits colorless fluorescence. Examples include, but are not limited to,
Derivatives of 4,4'-diaminostilbene-2,2'-disulfonic acid, coumarin derivatives such as 4-methyl-7-diethylaminocoumarin, 1-4-bis (O-cyanostyryl) benzol and 2-amino-4- There is methylphenol. The characteristics of this effective use of optical brighteners are unexpectedly favorable. This is because in the case of transmissive display materials, the ultraviolet light source is on the opposite side of the image, so that the ultraviolet light intensity is not reduced by the common ultraviolet filter in the imaging layer. As a result, less optical brightener is required to achieve the desired background color.

A photographic imaging element comprising a polymer sheet having at least one voided polyester skin layer and at least one non-voided polyester polymer layer comprises about 2 parts by volume of the voided layer of the polymer sheet. ~ 6
It is desirable to have 0% void space. Such a void concentration is desirable to optimize transmission and reflection properties and to provide sufficient diffusing power to hide the backlight and filament.

The biaxially stretched coextruded polymer sheet is
It may contain pigments known to improve the photographic optical response, such as brightness or sharpness. In the present invention, the sharpness and whiteness of an image are improved using titanium dioxide. The TiO ₂ used may be an anatase type or a rutile type. In the case of optical characteristics, a rutile type is preferable depending on its unique particle size and shape. Further, whiteness and sharpness may be improved by blending anatase type and rutile type TiO ₂ . An example of rutile TiO _{2 that} can be accepted by a photographic system is Dupond Chemical.
Co. R101 rutile TiO ₂ and Dupond
Chemical Co. R104 rutile TiO ₂
It is. Other pigments that improve photographic response, for example,
Barium, sulfate, clay, or calcium carbonate can also be used in the present invention.

Ti added to the biaxially stretched sheet of the present invention
The preferred weight% O ₂ is 4% to 18%. TiO ₂
If the addition amount is less than 3%, necessary light transmission cannot be easily achieved only by microvoiding. 4
Combining more than% TiO ₂ with voiding provides a low cost biaxially oriented microvoided sheet.
If TiO ₂ is greater than 14%, additional dye concentrations are needed to overcome the loss of permeability.

The preferred spectral transmittance of the day / night biaxially stretched polyester sheet of the present invention is 38 to 42.
%. This range is preferred because it looks best in either backlight or front view under daylight or room light conditions. Spectral transmittance is the amount of light energy transmitted through a substance. For photographic elements, spectral transmission is the ratio of transmitted intensity to incident intensity, expressed as a percentage, as follows: That is, T _RGB = 10 ^-D ×
Where D is X-Ritemodel
310 (or equivalent) is the average of the red, green and blue Status A transmission density responses measured by a photographic transmission densitometer. The higher the transmittance, the lower the opacity of the material. In the case of transmissive display materials that incorporate a diffuser, image quality is related to the amount of light that reflects from the image to the viewer's eyes. Transparent display images with low spectral transmission cannot adequately illuminate the image, causing a perceived loss of image quality. Transmission images having a spectral transmission of less than 35% are unacceptable as transmission display materials because their image quality cannot match that of prior art transmission display materials. In addition, if the spectral transmittance is less than 35%, additional dye concentration will be required, which will increase the cost of the transmissive display material. 40 spectral transmittance
% Provides acceptable image quality. But,
When the spectral transmission reached 75%, it was found that the material did not sufficiently diffuse the backlight illumination.

These biaxially stretched sheets improve the properties of the sheet, including printability, after co-extrusion and then a stretching step, or between casting and full stretching, and provide a vapor barrier. However, the sheet can be heat sealed or coated or treated with any number of coatings available to improve adhesion to the support or photosensitive layer. Examples of this coating include an acrylic resin coating for printability and a polyvinylidene chloride coating for heat sealing properties. Other examples include flame treatment, plasma treatment or corona discharge treatment to improve printability and adhesion.

In addition, either the conductive layer or the charge control layer may be provided as either an integral layer or a separate coating layer to minimize the occurrence of electrostatic glow or discharge in the photosensitive imaging member. It is also possible to Preferred embodiments include at least one photosensitive silver halide layer at the top of the photographic imaging member, at least one photosensitive silver halide layer at the bottom of the member, and at least one layer of voided polyester polymer and A photographic imaging member comprising a polymer sheet having at least one layer comprising a non-voided polyester polymer, wherein said imaging member has a transmittance of 38-42% and further comprises a tinting agent. And wherein the thickness of the non-voided layer is at least twice the thickness of the voided layer, and further wherein the member comprises a charge control agent or the polyethylene layer on top of a substrate member. Below is a photographic imaging member having at least one layer having a conductivity of less than 10 ¹¹ / □. In the case of a charge control layer that is integral with a layer having another function, or that is itself a functional layer, the charge control agent should be substantially neutral to the photosensitive emulsion or its protective overcoat.

The polyester utilized in the present invention must have a glass transition temperature of about 50 ° C. to about 150 ° C., preferably about 60-100 ° C., must be stretchable, and have an intrinsic viscosity. Must be at least 0.50, preferably 0.6-0.9. Suitable polyesters include those prepared from aromatic, aliphatic or cycloaliphatic dicarboxylic acids having 4 to 20 carbon atoms and aliphatic or cycloaliphatic glycols having 2 to 24 carbon atoms. There are polyesters made. Examples of suitable dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid,
There are naphthalenedicarboxylic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, itaconic acid, 1,4-cyclohexanedicarboxylic acid, sodiosulfoisophthalic acid, and mixtures thereof. Examples of suitable glycols include ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, 1,4-cyclohexane-dimethanol, diethylene glycol, other polyethylene glycols and mixtures thereof. Such polyesters are known in the art and can be prepared by known methods, for example, those described in U.S. Patent Nos. 2,465,319 and 2,901,466. A preferred continuous matrix polymer is a polymer containing a repeating unit derived from terephthalic acid or naphthalenedicarboxylic acid and at least one glycol selected from ethylene glycol, 1,4-butanediol and 1,4-cyclohexanedimethanol. It is united. Polyethylene terephthalate (may be modified with small amounts of other monomers)
Is particularly preferred. Polypropylene is also useful. Other suitable polyesters include liquid crystal copolyesters prepared with an appropriate amount of a co-acid component such as stilbene dicarboxylic acid. Examples of such liquid crystal copolyesters are the copolyesters described in U.S. Patents 4,420,607, 4,459,402 and 4,468,510.

Suitable crosslinked polymers for the microbeads used to form voids during sheet molding include:

The following formula:

Embedded image Wherein Ar is an aromatic hydrocarbon group or an aromatic halohydrocarbon group of the benzene series, and R is hydrogen or a methyl group;

The following formula:

Embedded image Wherein R is selected from the group consisting of hydrogen and an alkyl group containing from about 1 to 12 carbon atoms, and R 'is selected from the group consisting of hydrogen and methyl. Acrylate-type monomers containing: vinyl chloride and vinylidene chloride, acrylonitrile and vinyl chloride, vinyl bromide,

The following formula:

Embedded image (Wherein R is an alkyl group containing 2 to 18 carbon atoms); a copolymer of vinyl esters represented by the following formulas: acrylic acid, methacrylic acid, itaconic acid, citraconic acid,
Maleic acid, fumaric acid, oleic acid, vinylbenzoic acid;
Terephthalic acid and dialkyl terephthalic acid or an ester-forming derivative thereof, and HO (CH ₂ ) _n OH (wherein
n is an integer in the range of 2 to 10), which is a synthetic polyester resin having a reactive olefin bond in the polymer molecule thereof, wherein the reactive olefin unsaturated moiety is A polyester resin copolymerized with up to 20% by weight of a second acid or an ester thereof and a mixture thereof; a polymerizable organic material which is a member selected from the group consisting of: divinylbenzene, diethylene glycol It is selected from the group consisting of dimethacrylate, diallyl fumarate, diallyl phthalate and mixtures thereof.

Examples of common monomers used to produce the above crosslinked polymer include styrene, butyl acrylate, acrylamide, acrylonitrile, methyl methacrylate, ethylene glycol dimethacrylate, vinyl pyridine, vinyl acetate, Examples include methyl acrylate, vinylbenzyl chloride, vinylidene chloride, acrylic acid, divinylbenzene, arylamidomethyl-propanesulfonic acid, and vinyltoluene. As a crosslinked polymer, polystyrene or polymethyl methacrylate is preferred. Most preferably, the crosslinked polymer is polystyrene and the crosslinker is divinylbenzene.

Methods well known in the art result in particles of non-uniform size characterized by a broad particle size distribution. The resulting beads can be classified by screening the beads over the range of the original particle size distribution. Other methods, such as suspension polymerization with limited agglomeration, directly result in very uniform size particles. Suitable slip agents or lubricants include colloidal silica, colloidal alumina and metal oxides such as tin oxide and aluminum oxide. Preferred slip agents are colloidal silica and alumina, most preferably silica. Crosslinked polymers having a slip agent coating can be prepared by methods known in the art. For example, a normal suspension polymerization method in which a slip agent is added to a suspension is preferable. As the slip agent, colloidal silica is preferable.

It is preferred to use the "limited aggregation" method to produce coated crosslinked polymer microbeads. This method is described in detail in U.S. Pat. No. 3,615,972. However, when producing the coated microbeads used in the present invention, no blowing agent as described in this patent specification is used.

The following general method can be used for the limited aggregation method. 1. 1. Dispersing the polymerizable liquid in an aqueous, non-solvent liquid medium to produce a dispersion of droplets of a size no larger than desired as small particles of the polymer; The dispersion is allowed to settle, and then with little or no agitation, during which period the aggregation of the dispersed droplets is limited and the number of large droplets produced is small, Such agglomeration is limited by the composition of the suspending medium, so that the size of the dispersed droplets becomes significantly more uniform and desired, and then 3. The uniform droplet dispersion is then stabilized by adding a thickening agent to the aqueous suspension medium to further protect the uniform sized dispersion droplets from agglomeration and disperse. 3. Concentration of the dispersion is prevented from occurring due to the difference in density between the phase and the continuous phase, and then The polymerizable liquid phase and oil phase in the thus stabilized dispersion are polymerized under polymerization conditions, and as a result,
A spherical, remarkably uniform and desired sized polymer of small spheres is obtained, the size of which is mainly predetermined by the composition of the initial aqueous liquid suspension medium.

The diameter of the polymerizable liquid droplets, and thus the diameter of the polymer beads, can be varied from about 0.5 μm or less to about 0.5 cm by carefully varying the composition of the aqueous liquid dispersion. Can be changed as expected. Performing certain operations, the range of diameters of liquid droplets, and hence the diameter of polymer beads, is determined by the diameter of droplets and beads produced by normal suspension polymerization methods that employ deterministic stirring methods. Is in the order of 3 times or less in contrast to 10 times or more. Since the size, e.g., diameter, of the beads according to the method of the invention is mainly determined by the composition of the aqueous dispersion, the mechanical conditions such as the degree of agitation, the size and structure of the equipment used and the scale of operation are highly determined. Not a target.
Furthermore, by utilizing the same composition, the operation can be repeated or scaled,
And substantially the same result can be obtained.

The process of the present invention provides that 1 part by volume of the polymerizable liquid is at least 0.5 part by volume, preferably 0.1 part by volume, of a non-solvent aqueous medium containing water and at least the first of the following components: It is carried out by dispersing in 5 to about 10 or more volume parts. 1. A solid colloid dispersible in water and insoluble in water,
The particles have a size in the order of about 0.008 to about 50 nm in an aqueous medium and the particles tend to aggregate at the liquid-liquid interface or have the following components: 2. a water-soluble “promoter” that influences the “hydrophilic-hydrophobic balance” of the solid colloid particles; and / or 3. electrolyte; and / or 4. Colloid activity modifiers such as deflocculants and surfactants, and usually A water-soluble and monomer-insoluble polymerization inhibitor;

The water-insoluble and water-insoluble solid colloid may be an inorganic substance such as a metal salt or hydroxide or clay, or may be raw starch, a sulfonated crosslinked organic high polymer, or a resinous material. Organic substances such as polymers may be used.

The solid colloidal material must be insoluble but dispersible in water and insoluble and non-dispersible but wettable in the polymerizable liquid. The solid colloid must be much more hydrophilic than lipophilic so as to remain completely dispersed in the aqueous liquid. The solid colloid employed to limit agglomeration is a solid colloid having particles in an aqueous liquid that are relatively rigid and within a specified morphology and size within said limits. The particles can swell greatly and become highly hydrated, and if the swollen particles retain the correct morphology, then the effective size is approximately equal to the size of the swollen particles. The particles, in the case of a very high molecular weight crosslinked resin, may be especially single-molecules or may be aggregates of multiple molecules. A substance that disperses in water to form a true solution or colloidal solution and that diffuses in such a way that the size of the particles is smaller than the range described above or the particles lack a discernible form or size. Certain materials are not suitable as stabilizers used to limit aggregation. The amount of solid colloid that is employed is usually equivalent to for example, from about 0.01 to about 10g or more polymerizable per liquid 100 cm ^3.

To act as a stabilizer used to limit the aggregation of polymerizable liquid droplets, solid colloids
It is essential that it must readily assemble with the aqueous liquid at the liquid-liquid interface, i.e. at the surface of the oil droplets (the term "oil" is used generically here for water-insoluble liquids) May be used). In many instances, it is desirable to add a "promoter" substance to the aqueous composition to move the particles of the solid colloid to the liquid-liquid interface. This phenomenon is well known in the emulsion art,
As described in detail in adjusting the “hydrophilic-hydrophobic balance”, it is applied to solid colloid particles.

Usually, a promoter is an organic substance which has an affinity for solid colloids and oil droplets and which can make the solid colloid more lipophilic. Affinities for oil surfaces are usually based on certain organic moieties on the promoter molecule, whereas affinity for solid colloids is usually
It is based on the opposite charge. For example, positively charged metal complexes or hydroxides, such as aluminum hydroxide, are promoted by the presence of negatively charged organic promoters, such as water-soluble sulfonated polystyrenes, alginates and carboxymethylcellulose. Negatively charged colloids, such as bentonite, are positively charged promoters, such as tetramethylammonium hydroxide or chloride, or water-soluble, composite resinous amine condensation products, such as water-soluble condensation products of diethanolamine and adipic acid, ethylene oxide , Water-soluble condensation products of urea and formaldehyde, and polyethyleneimine. Amphoteric substances such as gelatin, glue, proteinaceous substances such as casein, albumin, glutin, etc. are effective promoters for a wide range of colloidal solids. Non-ionic substances such as methoxy-cellulose are also effective in some cases. Usually, promoters are used only to the extent of a few ppm of the aqueous medium, but higher ratios are often acceptable. In some cases, ionic substances normally classified as emulsifiers, such as soaps, long-chain sulfates and sulfonates, and long-chain quaternary ammonium compounds can also be used as promoters for solid colloids, but can be polymerized. Care must be taken to avoid the formation of a stable colloidal emulsion of liquid and aqueous liquid medium.

An action similar to that of an organic promoter can often be obtained with a small amount of a water-soluble and ionizable electrolyte such as alkalis, acids and salts, particularly an electrolyte having polyvalent ions. These are particularly useful where the excessive hydrophilicity or poor lipophilicity of the colloid is due to excessive hydration of the colloid structure. For example, a properly cross-linked sulfonated polymer of styrene will significantly swell and hydrate in water. Its molecular structure contains a benzene ring, which should give the colloid some sort of affinity for the oil phase in the dispersion, but due to its high degree of hydration, the colloidal particles are trapped in the cloud of associated water. Enclosed in When a soluble and ionizable polyvalent cation compound such as an aluminum salt or a calcium salt is added to the aqueous composition, the swollen colloid significantly shrinks, a part of the associated water exudes, and the organic Are exposed and the colloid becomes more lipophilic.

The particles of solid colloid whose hydrophilic-hydrophobic balance is such that the particles tend to collect in the aqueous phase at the oil-water interface are protected while collecting on the surface of the oil droplets and limiting aggregation. Functions as an agent.

Other agents that can be employed in a known manner to modify the colloidal properties of aqueous compositions include those known in the art such as deflocculants, flocculants and deflocculants, sensitizers, surfactants and the like. It is a known substance.

When dispersed in aqueous liquids or may be absorbed by colloidal micelles and polymerized in the aqueous phase, emulsions may be substituted for or in addition to the desired bead or pearl polymers A few ppm of a water-soluble, oil-insoluble polymerization inhibitor effective to prevent the polymerization of monomer molecules that tend to be a type of polymer dispersion,
It may be desirable to add to the aqueous liquid.

Then, the aqueous medium containing the water-dispersible solid colloid is mixed with the liquid polymerizable substance in such a manner that the liquid polymerizable substance is dispersed as small droplets in the aqueous medium. This dispersion is achieved by conventional means, for example by mechanical stirrer or shaker, jet pumping, impingement, or other methods of subdividing the polymerizable substance into droplets in a continuous aqueous medium. You.

For example, the degree of dispersion by agitation should be such that the size of the dispersed liquid droplets is not greater than the expected and desirable stable droplet size of a stable dispersion,
Much smaller is preferred. When such a state has been achieved, the resulting dispersion may be subjected to very gentle movement, depending on the case, but preferably without stirring. Under such a stationary state, the dispersed liquid phase has limited aggregation.

"Limited flocculation" means that droplets of liquid dispersed in a particular aqueous suspension medium agglomerate, but growing droplets (the number of which decrease as the size of the droplets grow) grow to a particular critical Is a phenomenon in which agglomeration is substantially stopped when a limited size is reached. The resulting droplets of the dispersed liquid can be as large as 0.3 cm and sometimes as large as 0.5 cm in diameter, but are quite stable for further agglomeration and are significantly uniform in size. When such large droplet dispersions are vigorously stirred, the droplets are subdivided into smaller droplets. The subdivided droplets, upon standing, re-agglomerate to the same limit, producing a stable dispersion of large droplets of the same uniform size. The dispersion obtained by limited coalescence is therefore stable for further flocculation and contains droplets of substantially uniform diameter. The basic principle of this phenomenon applies in the present invention to causing limited agglomeration in a planned and predictable manner to prepare a dispersion of a polymerizable liquid in the form of droplets of uniform and desired size. I was

In the phenomenon of limited agglomeration, small particles of solid colloid tend to collect with the aqueous liquid at the liquid-liquid interface, ie the surface of the oil droplets. Droplets substantially coated with such solid colloids are considered stable against aggregation, whereas uncoated droplets are not. In a given dispersion of a polymerizable liquid,
The total surface area of the droplet is a function of the total volume of the polymerizable liquid and the diameter of the droplet. Similarly, the total surface area that can be barely covered by a solid colloid, for example with a layer of one particle thickness, is a function of the amount of the colloid and the size of the particle. Initially, for example in a dispersion prepared by stirring, the total surface area of the polymerizable droplets is greater than the surface area that can be covered by the solid colloid. Under standing conditions, unstable droplets begin to aggregate. By its aggregation,
Until the amount of colloidal solids is barely sufficient to substantially cover the entire surface area of the oil droplet, the number of oil droplets has decreased and their total surface area has decreased, at which point agglomeration has occurred. Stop practically.

If the solid colloid particles are not of substantially the same size, their average effective size can be estimated by statistical methods.
For example, the average effective diameter of a spherical particle can be calculated as the square root of the average of the squares of the actual diameters of the particles of a representative sample.

It is usually advantageous to treat the homogeneous droplet suspension prepared as described above to render the suspension stable against agglomeration of the oil droplets.

This further stabilization can be achieved by gently mixing the homogeneous droplet dispersion with an agent that can greatly increase the viscosity of the aqueous liquid. To this end, a water-soluble or water-dispersible thickener that is insoluble in oil droplets and does not remove the layer of solid colloid particles covering the surface of the oil droplets at the oil-water interface. May be used. Examples of suitable thickeners are sulfonated polystyrene (water-dispersible thickening grades), hydrophilic clays such as bentonite, digested starch, natural gums, carboxy-substituted cellulose ethers and the like.
Thickeners are optionally used in amounts that produce a thixotropic gel in which droplets of oil of uniform size are suspended. In other words, the thickened liquid generally has a non-Newtonian flow behavior (i.e., prevents the dispersed droplets in the aqueous liquid from moving quickly under the action of gravity due to differences in phase density). Nature). The stress exerted by the suspension droplet on the surrounding medium is not sufficient to cause rapid movement of the droplet in such non-Newtonian media. Typically, the thickener is such that the apparent viscosity of the thickened aqueous liquid is on the order of at least 500 centipoise (typically measured on a Brookfield viscometer at 30 rpm using a No. 2 spindle). Used in proportion to aqueous liquid. The thickener is prepared as a separate concentrated aqueous composition and then carefully mixed with the oil droplet dispersion.

The resulting thickened dispersion can be handled, for example, by passing it through a pipe, and subjected to polymerization conditions with substantially no mechanical change in the size or morphology of the dispersed oil droplets. Can be attached.

The resulting dispersion comprises a coil which is applied to continuously introduce the thickened dispersion at one end and then continuously withdraw an assembly of polymer beads from the other end, Particularly suitable for use in continuous polymerization processes which can be carried out in tubes and elongated vessels. Further, the polymerization method can also be carried out in a batch system.

The order in which the components are added to the polymerization reaction is usually not critical, but water, a dispersant are added to the vessel, and the oil-soluble catalyst is added to the monomer mixture, followed by stirring.
Add the monomer phase to the aqueous phase.

The following is an example illustrating the procedure for producing cross-linked polymer microbeads coated with a slip agent. The polymer in this example is polystyrene cross-linked with divinylbenzene. The microbeads have a silica coating. The microbeads are produced by a method in which a droplet of a monomer containing an initiator is heated to a predetermined size to obtain a solid polymer sphere having the same size as the monomer droplet. The aqueous phase was 7 L of distilled water, 1.5 g of potassium dichromate (polymerization inhibitor for aqueous phase), 250 g of polymethylaminol adipate (promoter) and LUD
OX (colloidal suspension containing 50% silica, Du
Prepare by mixing 350 g (sold by Pont). The monomer phase is 3317 g of styrene, divinylbenzene (55% is an active crosslinker; the remaining 45% is ethylvinylbenzene, which forms part of a styrene polymer chain)
1421 g, and VAZ052 (monomer soluble initiator,
45 g) (prepared by Dupont). The mixture was passed through a homogenizer and
m droplets are obtained. The suspension was heated at 52 ° C. overnight,
The average diameter is about 5 μm, and the distribution width of the particle size is narrow (about 2 to 1
4.3 μg of nearly spherical microbeads
Get. The molar ratio of styrene and ethylvinylbenzene to divinylbenzene is about 6.1%. By adjusting the concentration of divinylbenzene up and down, depending on the active crosslinker, about 2.5-50% (preferably 10-40%)
Is carried out. Of course, monomers other than styrene and divinylbenzene can be used in similar suspension polymerization methods known in the art. Also, other initiators and promoters known in the art can be used. Other slip agents besides silica can also be used. For example, several LUs
DOX colloidal silicas are available from Dupont. LEPANDIN colloidal alumina is Deguss
a. NALCOAG colloidal silicas are available from Nalco, and tin oxide and titanium oxide are also available from Nalco.

Generally, when a polymer has suitable physical properties, such as resilience, the polymer is crosslinked. In the case of styrene cross-linked with divinylbenzene, the polymer is 2.5 to 50%, preferably 20 to 50%.
40% crosslinked. The percentage of crosslinking refers to the mole% of crosslinking agent relative to the amount of primary monomer. Such limited crosslinking produces microbeads that are sufficiently cohesive to remain intact during stretching of the continuous polymer.
Because such crosslinked beads also have resilience, the microbeads can be deformed (flattened) during stretching due to pressure from the matrix polymer on their opposing sides, but their To create the largest possible void around the microbeads and produce a less dense product.

These microbeads, as used herein, are meant to have a “slip agent” coating. By this term, it is meant that the friction on the surface of the microbeads is greatly reduced. actually,
This phenomenon is believed to be caused by silica acting as a miniature ball bearing on the surface. The slip agent can be formed on the surface of the microbeads during its formation by including it in the suspension polymerization mixture.

The size of the microbeads is controlled by the ratio of silica to monomer. For example, microbeads of the described size are generated at the following ratio. Microbead size Monomer Slip agent (silica) (μm) (parts by mass) (parts by mass) 2 10.4 15 27.0 1 20 42.4 1

The microbeads of the crosslinked polymer have a size range of from 0.1 to 50 μm and are present in an amount of from 5 to 50% by weight, based on the weight of the polyester. The microbeads made of polystyrene preferably have a Tg at least 20 ° C. higher than the Tg of the continuous matrix polymer and are harder than the continuous matrix polymer.

Since void formation generally increases due to the elasticity and resilience of the microbeads, it is preferred that the Tg of the microbeads be as high as possible than the Tg of the matrix polymer to avoid deformation during stretching. It is not believed that there are practical benefits of crosslinking beyond the resilience and elasticity issues of microbeads.

The crosslinked polymer microbeads are at least partially adjacent to the voids. The void space of the support is 2-60% by volume of the film support, preferably 30%.
It must account for ~ 50% by volume. Depending on the manner in which the support is manufactured, the voids can completely surround the microbeads. For example, the void may be in the form of a donut (or flat donut) surrounding the microbead, or the void may be adjacent to only a portion of the microbead, for example, a pair of voids on opposite sides of the microbead. May be adjacent.

During stretching, the voids take on characteristic morphologies from balanced biaxial stretching of the paper-like film to uniaxial stretching of the microvoided / satin-like fibers. The balanced microvoids are mainly circular in the drawing plane, while the microvoids of the textile extend in the direction of the axis of the textile. The size of the microvoids and the final physical properties are determined by the balance between the degree of stretching and the stretching, the stretching temperature and the stretching speed, the kinetics of crystallization, the particle size distribution of the microbeads and the like.

The film support of the present invention is manufactured as follows. That is, (a) preparing a mixture of a molten continuous matrix polymer and a cross-linked polymer, the cross-linked polymer being a number of microbeads uniformly dispersed throughout the matrix polymer, and The polymer as described, the crosslinked polymer microbeads being the beads as described above, and (b) producing a film support from the mixture by extrusion or casting, and (c) stretching the product Stretching to produce cross-linked polymer microbeads that are evenly distributed throughout the product, and voids that are at least partially adjacent to the microbeads in one or more directions of stretching.

The above-mentioned mixture can be produced by preparing a melt of the matrix polymer and mixing it with the crosslinked polymer. The crosslinked polymer may be in the form of solid or semi-solid microbeads. Since the matrix polymer and the cross-linked polymer are incompatible with each other, there is no attractive force or adhesion between them, so that upon mixing, the microbeads are uniformly dispersed in the matrix polymer.

Once the microbeads have been uniformly dispersed in the matrix polymer, a film support is formed by methods such as extrusion or casting. Examples of extrusion or casting are:
Extrusion or casting of a film or sheet. Such molding methods are known in the art. When casting or extruding sheet or film material, such products are
It is important to stretch by stretching in at least one direction. Methods for stretching a sheet or film material in one or two directions are known in the art.
Basically, such a method consists of casting or extruding a sheet or film and then stretching it at least about 1.5 to 10 times its original dimension in the machine or longitudinal direction. Also, such sheets or films may be oriented in the transverse direction, ie, the direction crossing the machine direction, by approximately 1.5 to 10 times their original dimensions (typically 3 times for polyester) by equipment and methods known in the art. -4 times and 6-10 times in the case of polypropylene). Such devices and methods are known in the art and are described in U.S. Pat. No. 3,903,234.

Since the continuous matrix polymer is stretched at a temperature above its Tg, the voids or void spaces described herein are formed around the microbeads. Crosslinked polymer microbeads are harder than continuous matrix polymers. Also, since microbeads and matrix polymer are incompatible and immiscible with each other,
The continuous matrix polymer slides on the microbeads as it is stretched, creating voids on one or more stretch sides, the voids becoming elongated as the matrix polymer continues to stretch. Thus, the final size and shape of the void is determined by the direction or directions of stretching and the size of the stretching. If the stretching is in only one direction, the microvoids will form on the side of the microvoids in the direction of the stretching. If the stretching is bidirectional (bidirectional stretching),
Such a stretch has a vector component extending radially from a given location, resulting in a donut-shaped void surrounding each microvoid.

The preferred stretching operation of the preform simultaneously opens the microvoids and stretches the matrix material. The properties of the final product can be determined and controlled by the relationship between stretching time and temperature and the type and degree of stretching. For maximum opacity and texture, stretching is performed at a temperature just above the glass transition temperature of the matrix polymer. If stretching is performed near a higher glass transition temperature, both phases are stretched together, reducing opacity. In the former case, these materials are pulled separately, which is due to the mechanical compatibilization method (anticomp
atibolization). Two examples are high speed melt spinning of fibers and melt blowing of fibers and films to produce nonwoven / spunbond products. In summary,
The scope of the present invention includes the full scope of the molding operation described above.

In general, voids are formed independently of and do not require the crystallographic orientation of the matrix polymer. Opaque microvoided films are produced according to the method of the present invention using amorphous, non-crystalline copolyesters as the matrix phase. Crystalline / oriented (strain hardening) matrix materials are preferred for obtaining certain properties such as tensile strength and gas permeation barrier. On the other hand, amorphous matrix materials have particular utility in other areas such as tear resistance and heat sealability. Special matrix compositions can be tailored to meet the needs of many products. The entire range of matrix polymers, from crystalline to amorphous, is part of the present invention.

Since TiO ₂ in the transparent polymer gives the reflective display material an unfavorable pearlescent appearance,
Transparent polymer beads without iO ₂ are preferred. In addition, TiO ₂ is deposited over the entire thickness (generally, 100 μm to 18 μm).
0 μm), the prior art TiO ₂ colored transparent polymers are expensive. Also, T
iO ₂ provides a slightly yellowish transparent polymer which is undesirable for photographic display materials. When used as a reflective photographic display material, tints a transparent polymer support containing TiO ₂ to blue to reduce the desired whiteness and offset the yellow tint of the polymer, adding cost to the display material Must. The concentration of white pigment in the polyolefin layer allows for efficient use of white pigment, improving image quality and reducing the cost of the imaging support.

In the preparation of photographic elements, it is important to design the photographic elements to transport them efficiently through the processing equipment to minimize jamming and other problems. In such a case, the back surface of the image forming member has a thickness of 0.3-2.
It should have a roughness of 0 μm. This range of roughness helps improve frictional properties and optimizes photofinishing and transport of this material. Further, it is preferable to control the roughness characteristics of the top surface. In this case, it is desirable to introduce roughness on the image side of the element to help prevent fingerprints and damage. The improved roughness also helps in assembling the display. This is because the slightly uneven surface easily slides into the display frame with the protective overcover. In addition, a roughened surface provides the additional benefit of reducing gloss for applications that create a softer atmosphere or message with this imaging material. Also, the photographic image forming element of the present invention may be such that the top of the image forming member has a thickness of 0.02 to
May be designed to have a surface roughness of

When the silver halide image forming layer is a polyethylene
Coated on the skin and gelatin coating layer, preferably
The structure of the new biaxially stretched coextruded sheet is as follows:
You. Polyethylene containing a bluing agent Microvoided polyester containing a fluorescent brightener and TiO ₂ Solid polyester core Coated gelatin layer

For the display materials of the present invention, it is preferred that at least one image layer containing silver halide and a dye-forming coupler be located on top or bottom of said imaging element. Applying the imaging layer to the top or bottom is preferred for photographic display materials, but not enough to create an optimal photographic display material for transmissive displays. For the display materials of the present invention, it is preferred that at least one image layer containing at least one dye-forming coupler be located on both the top and bottom of the imaging support of the present invention. When the image layer is coated on both the top and bottom of the support, a thin photosensitive layer can be used to optimize image density while reducing development time to less than 50 seconds.

The at least one dye-forming layer on the opposite side of the transparent polymer sheet from the biaxially oriented polyolefin sheet has less dye-forming coupler than the image-forming layer on the same side as the biaxially oriented polyolefin sheet. Preferred display materials of the present invention are: The ratio of the coating amount on the top side to the bottom side of the double emulsion is 1: 0.6 to 1:
It has been found that it is better to be within the range of 1.25.
The ratio of the top side to the bottom side coverage of the double emulsion is 1:
At 1.25, it was found that the imaging light was large and conversely attenuated and the bottom emulsion coating was underexposed. In contrast, when the ratio of the top side to the bottom side coverage of the double emulsion was less than 1: 0.6, the imaging light was large and inversely attenuated and the top emulsion coating was overexposed. . The preferred ratio of the top side to the bottom side coverage of the double emulsion is 1: 1. A 1: 1 ratio can achieve the necessary exposure and dye density required to obtain a high quality image. Most preferred is the display material of the present invention wherein the at least one dye-forming layer on the opposite side contains about the same amount of dye-forming coupler as the imaging layer on the same side as the biaxially oriented polyolefin sheet. Coating both sides with substantially the same amount of a light-sensitive silver halide emulsion has the additional benefit of balancing the imaging element against image curl caused by the shrinkage and expansion of the hygroscopic gelatin commonly found in photographic emulsions. There are advantages.

The term "photographic element" or "image forming element" as used herein is a material that utilizes photosensitive silver halide to form an image. These photographic elements may be single color elements or multicolor elements. Multicolor elements contain image dye-forming units sensitive to each of the three primary regions of the spectrum. Each unit may contain a single emulsion layer or multiple emulsion layers sensitive to a given region of the spectrum. The layers of the photographic element, including the layers of the image-forming units, can be arranged in various orders as known in the art. In another format, emulsions sensitive to each of the three primary regions of the spectrum may be arranged as a single segmented layer.

For the display materials of the present invention, it is preferred that at least one image layer containing silver halide and a dye-forming coupler be located on top or bottom of said imaging element. It is preferred to apply the imaging layer to the top or bottom to obtain a high quality photographic transmissive display material. In some markets, there is a need to increase dye density to improve image quality. Increasing the dye concentration increases the amount of light-sensitive silver halide emulsion coated on one side. Although the image quality improves with increasing emulsion coverage, the development time increases from 50 seconds to 110 seconds. For the display materials of the present invention, it is preferred that at least one image layer containing at least one dye-forming coupler be located on both the top and bottom of the imaging support of the present invention. When the image layer is coated on both the top and bottom of the support, the development time is reduced by 5 minutes using a thin photosensitive layer.
The image density can be optimized while being shorter than 0 seconds.

Most preferred are display materials of the present invention in which the top at least one dye-forming layer contains about the same amount of dye-forming coupler as the backside imaging layer. Coating both sides with substantially the same amount of a light-sensitive silver halide emulsion balances the imaging element against image curl caused by shrinkage and expansion of the hygroscopic gelatin commonly used in photographic emulsions. There are additional benefits.

The photographic emulsions useful in the present invention are generally prepared by precipitating silver halide crystals in a colloid matrix in a manner conventional in the art.
The colloid is generally an agent that forms a hydrophilic film, such as gelatin, alginic acid or derivatives thereof.

The crystals formed in the above precipitation step are washed, then the spectral sensitizing dye and the chemical sensitizer are added and then heated to raise the temperature of the emulsion, generally from 40 ° C. to 70 ° C., for a period of time. Maintain chemical sensitization and spectral sensitization. Used to produce the emulsion utilized in the present invention,
The methods of precipitation, spectral sensitization and chemical sensitization may be those known in the art.

To chemically sensitize the emulsion used in the present invention,
Generally, sulfur-containing compounds such as allyl isothiocyanate, sodium thiosulfate and allyl thiourea; reducing agents such as polyamines and stannous salts; noble metal compounds such as gold, platinum; and polymeric agents such as polyalkylene oxides Sensitizers such as are used. The chemical sensitization is completed by employing the heat treatment as described above. Spectral sensitization is performed by combining dyes, which are designed for a desired wavelength range in the visible or infrared spectrum. It is known to add such dyes before and after heat treatment.

After spectral sensitization, the emulsion is coated on a support. Various coating methods include dip coating, air knife coating, curtain coating and extrusion coating.

The silver halide emulsion used in the present invention is:
Any type of halide may be contained. Thus, the emulsions are comprised of silver chloride, silver bromide, silver bromochloride, silver chlorobromide, silver iodochloride, silver iodobromide, silver bromoiodide, silver chloroiodobromide, silver iodobromochloride and iodochlorobromide. It may contain a silver emulsion. However, the emulsion of the present invention is preferably mainly a silver chloride emulsion. Predominantly silver chloride means that the emulsion grains are greater than about 50 mole percent silver chloride. Preferably, the emulsion grains contain greater than about 90 mole percent silver chloride and optimally greater than about 95 mole percent silver chloride.

The halogenated emulsion used in the present invention may contain grains of any size and form. Thus, the grains may be in the form of cubes, octahedrons, octahedrons, or other naturally occurring forms of cubic lattice silver halide grains. Further, these grains may be irregular grains such as spherical grains or tabular grains. Tabular or cubic grains are preferred.

The photographic elements of the present invention are described in "The James
Theory of the Photographic Process, 4th edition, 151-
152 pages, 1977, Macmillan Publishing Company, Inc.
The emulsions described in (1) can be used. It is known that reduction sensitization improves the photographic sensitivity of silver halide emulsions. Although reduction sensitized silver halide emulsions generally exhibit excellent photographic sensitivity, they often cause undesirable fog and poor storage stability.

Reduction sensitization can be accomplished by adding a reduction sensitizer, ie, a chemical agent that reduces silver ions to form metallic silver atoms, or by increasing the pH (excess hydroxide ions) and / or lower pAg ( It can be done intentionally by providing a reducing environment (excess silver ions). Unintentional reduction sensitization can occur during precipitation of a silver halide emulsion, for example, when a silver nitrate or alkali solution is added rapidly or with insufficient mixing to form emulsion grains. is there. Further, when a silver halide emulsion is precipitated in the presence of a ripening agent (a grain growth modifier) such as thioethers, selenoethers, thioureas or ammonia, reduction sensitization tends to be promoted.

Examples of reduction sensitizers and environments that can be used during precipitation or spectral / chemical sensitization to reduce sensitize emulsions are described in US Pat. Nos. 2,487,850 and 2,512,92.
No. 5 and British Patent 789,823, ascorbic acid derivatives, tin compounds, polyamine compounds and thiourea dioxide-based compounds. Specific examples of reduction sensitizers or conditions such as dimethylamine borane, stannous chloride, hydrazine, high pH (pH 8-11)
And aging at low pAg (pAg1-7) are described in S. C.
ollier, Photographic Science and Engineering, Volume 23
Considered on page 113, 1979. An example of a method for intentionally producing a reduction sensitized silver halide emulsion is described in EP-A-0 348 934 A1 (Yamashit.
a), No. 0369491 (Yamashita),
Nos. 0371388 (Ohashi) and 0396
424A1 (Takada), 0404142A
No. 1 (Yamada) and No. 0435355A1 (Makino).

The photographic elements of the present invention are available from Kenneth Maso, Dudley Annex, 12a North Street, Emsworth, P0107DQ, Hampshire, England.
n Research Disclosure published by Publications, Ltd., September 1994, Item
Emulsions doped with Group VIII metals such as iridium, rhodium, osmium and iron as described in 36544, Section I may be used. In addition, a general summary of the use of iridium to sensitize silver halide emulsions can be found in Carrol, "Iridium Sensitization: A Liter
ature Review ", Photographic Sience and Engineerin
g, Vol. 24, No. 6, 1980. A method for preparing a silver halide emulsion by chemically sensitizing the emulsion in the presence of an iridium salt and a photographic spectral sensitizing dye is disclosed in U.S. Pat.
93,965. In some cases where such dopants were added, the emulsion was
When processed by the color reversal E-6 method as described in ournal of Photography Annual, 1982, pp. 201-203, the sensitometric curve shows increased fresh fog and low contrast.

The general multicolor photographic element of the present invention comprises a cyan dye image-forming unit comprising at least one red-sensitive silver halide emulsion layer having at least one cyan dye-forming coupler; Magenta image-forming units comprising at least one green-sensitive silver halide emulsion layer having a magenta dye-forming coupler associated therewith; and at least one blue-sensitive silver halide emulsion having at least one yellow dye-forming coupler associated therewith It has a layered support of the invention that holds yellow dye image forming units comprising a layer. The element may contain additional layers such as filter layers, interlayers, overcoat layers, subbing layers, and the like. The support of the present invention can also be used in black-and-white photographic print elements.

The above photographic element is disclosed in US Pat.
As described in 79,945 and 4,302,523, a transparent magnetic recording layer such as a layer containing magnetic particles may be provided on the lower surface of a transparent support.
Generally, this element has a total thickness (including the support) of about 5 to about 5 mm.
It is about 30 μm.

The elements of the present invention may employ the materials disclosed in Research Disclosure, 40145, September 1997, and particularly the couplers disclosed in Section II of this Research Disclosure.

The following table shows (1) Research Disclosure, December 1978, Item 17643, (2) Research Disclosure, December 1989, Item 308119,
And (3) Research Disclosure, September 1994,
Quote item 36544. These references are all published by Kenneth Mason Publications, Ltd., Dudley Annex, 12a North Street, Emsworth, P0107DQ, Hampshire, England. In the table below and the references cited in the table,
Certain components suitable for use in the elements of the present invention are described. The following table and references therein also describe suitable methods for preparing, exposing, processing and then manipulating the elements of the present invention to obtain the images contained therein.

[0105] Reference No. Section Theme 1 I, II Particle composition, morphology and preparation; Hardening 2 XI, XII, XIV, XV Emulsion preparation 3 I, II , including agents, coating aids, additives, etc. , III, IX A & B 1 III, IV Chemical sensitization and spectral sensitization / desensitization 2 III, IV 3 IV, V 1V UV dye, Fluorescent brightener, 2V fluorescent dye 3 VI 1VI Antifoggant and stable Agent 2 VI 3 VII 1 VIII Absorbing and scattering material; Antistatic layer 2 VIII, XIII, XVI; Matting agent 3 VIII, IX C & D 1 VII Image coupler and image modified cap 2 VII Revision 3 X Good agent 1 XVII support 2 XVII 3 XV 3 XI Specific layer arrangement 3 XII, XIII negative emulsion; direct positive emulsion 2 XVIII exposure 3 XVI 1 XIX, XX chemical treatment; developing agent 2 XIX, XX, XXII 3 XVIII, XIX, XX 3 XIV Scanning and digital processing method

The photographic elements of the present invention can be used in various forms of energy, including the ultraviolet, visible and infrared regions of the electromagnetic spectrum, as well as electron beams, β-rays, γ-rays, X-rays, α-particles, neutrons, Non-coherent (random phase) or coherent (in-phase) as generated by a laser
The mold can be exposed to other forms of particulate and wavy radiant energy. The photographic elements of the present invention, when intended for exposure to X-rays, may have features found in conventional radiographic elements.

For an imaging method comprising providing a photographic member comprising at least one layer of a voided polyester polymer and at least one layer of a non-voided polyester polymer, the imaging member has a transmittance of 40 ~ 60%
Preferably, the non-voided layer is at least twice as thick as the voided layer, and the photographic member is exposed to a collimated coherent light source. The imaging element of the present invention is preferably exposed to a collimated beam to produce a latent image and then processed, preferably by a method other than heat treatment, to obtain a visible image. A collimated beam is preferred. Because the beam allows digital printing and simultaneous exposure of the top and bottom imaging layers without significant internal light scattering. A preferred example of a collimated beam is a laser known as light amplification by stimulated emission.
Lasers are preferred because they are widely used in many types of digital printing devices. Further, the laser provides sufficient energy to simultaneously expose the top and bottom photosensitive silver halide coatings of the display material of the present invention without unwanted light scattering. Subsequent processing for converting the latent image into a visible image is preferably performed using a known RA-4.
(Trademark) (Eastman Kodak Company) method or other processing methods suitable for developing high chloride emulsions.

The imaging element comprises one dye-forming layer containing silver halide and a dye-forming coupler on the opposite side of the transparent polymer sheet from a biaxially oriented polyolefin sheet, and both layers containing the coupler. Preferred is the day / night dual display material of the present invention wherein the exposure is from the side of the imaging element having the biaxially oriented polyolefin sheet. This makes it possible to use a conventional image processing device. The imaging element of the present invention is preferably exposed using a collimated beam to produce a latent image and then processed, preferably by a method other than heat treatment, to obtain a visible image. A collimated beam is preferred. Because the beam allows digital printing and simultaneous exposure of the top and bottom imaging layers without significant internal light scattering. A preferred example of a collimated beam is a laser known as light amplification by stimulated emission. Lasers are preferred because they are widely used in many types of digital printing devices. In addition, the laser
It provides sufficient energy to simultaneously expose the top and bottom photosensitive silver halide coatings of the display materials of the present invention without unwanted light scattering. The subsequent processing for converting the latent image into a visible image is preferably performed by the known RA-4 method or by another processing method suitable for developing a high chloride emulsion.

[0109]

EXAMPLE 1 In this example, the present invention was compared to a typical prior art transmissive display material. The present invention was a double silver halide emulsion coated support having a thin skin layer of polyethylene on top of a microvoided layer integrally bonded to a transparent polyester substrate. Prior art materials and the present invention were measured for transmittance%, brightness, color, and illumination transmission. This example shows a reduction in yellow color in the minimum density region and a reduction in development time compared to prior art materials.

The following prior art transmissive display materials were used for comparison with the present invention. Kodak Duratrans (Eastm
an Kodak Co.) is a one-sided silver halide coated polyester support having a thickness of 180 μm. The support is a clear gelatin subbed polyester. This silver halide emulsion contained 215 rutile-type TiO ₂ in the bottom layer.
0 g / m ² (200 g / ft ² ). The following day / night photographic display materials of the present invention were prepared by extrusion of a biaxially oriented polyester sheet having a microvoided skin layer with a second skin layer on top of the microvoided skin layer. The core of the substrate of this structure was a bottom-primed transparent polyester having an adhesion promoting material that enhanced the adhesion of the photosensitive emulsion-derived gelatin to the imaging member.

The fluorescent whitening agent used was Hostalux.
 KS (Ciba-Geigy). Anatase
Type TiO_Two Was added at 10% by weight of the base polymer. T
iO _Two Is Kronos 1014 (with a particle size of 0.22 μm).
TiO_Two )Met. Table I below shows the top two used in this example.
The characteristics of the layers of the axially stretched sheet are shown.

[0112]

[Table 1]

Low-density polyethylene (LDPE) is available from Eastman Ch.
amical D4002P (0.917 g / cm ³ ) and Dupo
nt Bynel 2169 was added at 35% by weight with 0.07% Pigment Blue 60. Optical brightener is Hostalu
x KS (Ciba-Geigy) and the gelatin subbing layer was a gelatin-based layer that promoted adhesion between the polyester and the photosensitive layer.

Using coating format 1, day / night photographic display materials were prepared and coated on top of the L1 polyethylene layer on top coextruded biaxially oriented polyester sheet. The same coating coverage was coated both on the L1 polyethylene layer on the top coextruded biaxially oriented polyester sheet and on the bottom gelatin subbing layer.

Coating Format 1 Laydown mg / m ² Layer 1: Blue Sensitive Layer Gelatin 1300 Blue Sensitive Silver 200 Y-1440 ST-1440 S-1190

Layer 2: Intermediate layer Gelatin 650 SC-1 55 S-1 160 Layer 3: Green sensitive layer Gelatin 1100 Green sensitive silver 70 M-1 270 S-1 75 S-232 ST-2 20 ST-3 165 ST-4 530

Layer 4: UV interlayer Gelatin 635 UV-1 30 UV-2 160 SC-1 50 S-3 30 S-1 30 Layer 5: Red sensitive layer Gelatin 1200 Red sensitive silver 170 C-1 365 S-1 360 UV-2 235 S-4 30 SC-13

Layer 6: UV Overcoat Gelatin 440 UV-1 20 UV-2 110 SC-1 30 S-3 20 S-1 20 Layer 7: SOC Gelatin 490 SC-117 SiO ₂ 200 Surfactant 2

Reagents used

Embedded image

ST-1 = Nt-butylacrylamide / n-butylacrylate copolymer (50:50) S-1 = dibutylphthalate

[0121]

Embedded image S-2 = diundecyl phthalate

[0122]

Embedded image S-3 = 1,4-cyclohexyldimethylenebis (2-
Ethylene hexanoate)

[0123]

Embedded image S-4 = 2- (2-butoxyethoxy) ethyl acetate

[0124]

Embedded image

The construction of the photographic day / night element of this invention of this example was as follows: Coating Format 1 DuPont Bynel + Voided Polyester with TiO ₂ Low Density Polyethylene OB Transparent Polyester Base Gelatin Primer Coating Coating Format 1

The above-mentioned display material is used as a minimum concentration.
Processed. X-Rite
Status A using a Model 310 photographic densitometer
The permeation concentration was measured. Spectral transmittance status
Calculated from the reading of A concentration,
The ratio of degrees, expressed as a percentage as follows: T_{RG B}
= 10^-D× 100 (where D is a red, green and blue stator
The average value of the response of the transmission density of the sample A). Also,
The display material is Sp Sp using light source D6500.
Using an electrogard spectrophotometer, CIE system, L
^*, A^*And b ^*Was measured. In the transmission mode, the illumination light
The amount of permeation was quantitatively evaluated. See through
Larger amounts are considered undesirable. Because it is light
This is because if the source is seen through, the image quality is impaired. The present invention
And control data are listed in Table II below.

[0127]

[Table 2]

The day / night display support coated on the top and bottom with the photosensitive silver halide coating format of this example exhibits all the properties required for transmissive photographic and reflective display materials. Furthermore, the day / night display material of this example has many advantages over prior art photographic display materials. The non-voided layer was adjusted to provide an improved minimum density condition over prior art transmissive display materials so that the present invention could overcome the inherent yellowness of the processed emulsion layer. Containing a level of TiO ₂ and a colorant (b ^* of the permeable material of the invention is one of the permeable materials of the control)
3.59 compared to b ^* of 1.14). In the transmissive mode, the backlight illumination is not visible through the material of the present invention, indicating an excellent transmissive product compared to the prior art.

Since the transmittance of the material of the present invention was 39%, an excellent transmission image was obtained. This is because more light is transmitted from the illumination source. Furthermore, by concentrating the colorant and white pigment in the biaxially stretched sheet,
Improved manufacturing efficiency and less material usage is possible, resulting in lower cost display materials compared to the prior art. The a ^* and L ^* of the material of the present invention are consistent with high quality transmissive display materials.

Surprisingly, when an image is printed on the material of the present invention by exposing only the top side with a laser,
No distortion was observed in the reverse image. This allows simultaneous printing of the top imaging layer and the bottom imaging layer without misaligning the images. The addition of the voided layer allowed the opacity necessary to prevent the filament from seeping through, and also allowed simultaneous imaging of the top and bottom surfaces without distortion of the bottom image. Finally, the present invention provides a 4 to 1 development time compared to the prior art transmissive display material which has a development time of 110 seconds.
The development time was 5 seconds. A development time of 45 seconds has great commercial value in that this display material of the present invention can greatly increase the productivity of the processing equipment.

[0131] Other preferred embodiments of the present invention are described below in connection with the claims. (Aspect 1) At least one photosensitive silver halide layer on the top of a photographic imaging member, at least one photosensitive silver halide layer on the bottom of the member, and at least one layer of a voided polyester polymer and A photographic imaging member comprising a polymer sheet having at least one layer comprising a nonvoided polyester polymer, wherein said imaging member has a transmittance of 38-42% and further comprises a tinting agent. A photographic imaging member comprising, wherein the thickness of the non-voided layer is at least twice the thickness of the voided layer. (Aspect 2) Aspect 1 in which the polymer sheet is stretched
3. The photographic image forming member according to 1.

(Embodiment 3) The photographic image forming member according to embodiment 1, wherein the polymer sheet comprises at least one polyethylene layer. (Aspect 4) The photographic image forming member according to Aspect 1, wherein the member further includes at least one undercoat layer. (Aspect 5) Aspect 1 wherein the void space constitutes about 2 to 60% by volume of the voided layer of the polymer sheet.
3. The photographic image forming member according to 1. (Aspect 6) The thickness of the image forming member is 76 to 256 μ.
m. The photographic image forming member according to aspect 1, wherein m.

(Embodiment 7) The photographic image forming member according to embodiment 1, wherein the tinting agent contains a bluing agent. (Embodiment 8) The photographic image-forming member according to embodiment 1, wherein the polymer sheet contains a fluorescent whitening agent. (Embodiment 9) The photographic image forming member according to embodiment 1, wherein the polymer sheet contains a white pigment. (Aspect 10) The photographic image forming member according to Aspect 1, wherein the photographic image forming member further includes an antihalation layer. (Embodiment 11) The photographic imaging member according to embodiment 1, wherein the top layer and the bottom layer comprise a photosensitive silver halide and a dye-forming coupler.

(Aspect 12) The photographic image forming member is:
In addition, polyethylene on top of the voided polyester layer
The photographic image forming section according to embodiment 1, comprising a polymer layer
Wood. (Aspect 13) The lower part of the lower side of the polyethylene-containing layer
And one layer is 10 ¹¹Log-ohms / smaller
Aspect 1. Embodiment 1 comprising a charge control agent having air resistivity
Photographic image forming member. (Aspect 14) The voided layer is used for the voided layer.
Contains organic particles that are void formation initiators
A photographic image forming member according to aspect 1.

(Aspect 15) The photographic image forming member according to aspect 1, wherein the back surface of the image forming member has a surface roughness of 0.3 to 2.0 μm. (Aspect 16) The image forming member has a top portion of 0.02 to 0.02.
2. The photographic image forming member according to embodiment 1, having a surface roughness of 0.2 μm. (Aspect 17) The photographic image forming member according to Aspect 1, wherein the thickness of the voided layer is 6 to 50 μm. (Aspect 18) At least one photosensitive silver halide layer on the top of the photographic imaging member, at least one photosensitive silver halide layer on the bottom of the member, and at least one layer of voided polyester polymer and A photographic imaging member comprising a polymer sheet having at least one layer comprising a nonvoided polyester polymer, wherein said imaging member has a transmittance of 38-42% and further comprises a tinting agent. Providing a photographic imaging member containing, and wherein the thickness of the non-voided layer is at least twice the thickness of the voided layer, and exposing the photographic imaging member to a collimated coherent light source An image forming method comprising: (Embodiment 19) At least one layer below the polyethylene-containing layer has an electrically neutral charge in relation to the backside layer of the element and the topmost layer of the photosensitive silver halide emulsion layer. The photographic image forming member according to embodiment 1, which comprises a charge control agent. Although the present invention has been described in detail with particular reference to certain preferred embodiments thereof, various modifications can be made within the spirit and scope of the invention.

[0136]

The present invention provides a brighter image by more efficiently diffusing the light used to illuminate the display material.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Alphonse D. Camp United States, New York 14612, Rochester, Whispering Pines Circle 616 (72) Inventor Peter Tee. Isleward United States, New York 14468, Hilton, Haskins Lane North 92

Claims (1)

[Claims] At least one photosensitive silver halide layer on top of a photographic imaging member, at least one photosensitive silver halide layer on the bottom of the member, and at least one layer of a voided polyester polymer. And a polymer sheet having at least one layer containing a non-voided polyester polymer, wherein the image forming member has a transmittance of 38-42%, and a tint. And wherein the thickness of the non-voided layer is at least twice the thickness of the voided layer.